This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project focuses on the relationship of structure to function in heme proteins. An area of particular interest is the acquisition and utilization of heme by bacterial pathogens such as Shigella dysenteriae, Neisseriae meningitidis and Corynebacterium diphtheriae. Iron is essential for the survival of all bacteria and many pathogenic bacteria have developed sophisticated mechanisms by which they utilize the hosts heme containing proteins as a source of iron. The ability of pathogenic bacteria to acquire iron is in part linked to their virulence. Understanding the mechanism of heme uptake and iron release at the molecular level will allow rational design of therapeutic agents for the treatment of bacterial infections. The expression and characterization of the outer-membrane receptor (Shu A), periplasmic binding protein (ShuT) and a heme-DNA binding hemeprotein (Shu S) from S. dysenteriae will allow characterization of the the heme transport proteins. In addition the recent expression of heme degrading enzymes from C. diphtheriae (HmuO) and Neisseriae meningitidis (HemO) have allowed the mechanism of iron release to be investigated. Site-directed mutagenesis together with biophysical techniques such as optical absorption, resonance Raman, NMR and X-ray crystallography are used to determine the structural features required for heme binding, transport and catalysis. Software available at CGL, especially Chimera, Midas and Sparky will be used extensively to analyze and view the NMR data and structures of these molecules.